DARPA image technology would move way beyond X-Rays

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A digital camera took an overhead picture of the open cask (left) and a neutron imaging system photographed the lilies through the lead walls of the cask (right). This image demonstrates the power of neutrons to easily pass through otherwise "impenetrable" materials, such as the lead cask, and yet have enough sensitivity to reveal fine details such as the leaf veins of the Asiatic lilies. The neutron image has been sharpened slightly to improve black-and-white contrast for viewing on the web. (NIST Photo/caption)

Getting a better view inside mostly dense objects like corrosion in aircraft wings and welds on ships or even gunpowder hidden in suitcases are just a few of the applications researchers at the Defense Advanced Research Projects Agency are hoping to develop with a new program called Intense and Compact Neutron Sources (ICONS).

With ICONS DARPA is actually looking to develop a portable unit able to generate both neutrons and X-rays.

“X-Ray imaging has proven invaluable in a host of military and commercial applications—from spotting tiny cracks in aircraft wings, to making medical diagnoses, to scanning passengers’ bags to keep the flying public safe. As useful as X-ray scanning is, however, it is limited in what it detects. For example, while X-ray radiography can highlight heavier chemical elements very well (think of shiny silver fillings on a dental X-ray), it’s not very good at revealing lighter elements, such as hydrogen. That’s why X-ray radiography machines are generally “blind” to water or other liquids,” DARPA stated.

By contrast, neutron radiography—which uses neutrons to image objects—is very good at visualizing lighter elements and liquids, in some cases even identifying a substance’s atomic makeup. Unfortunately, neutron sources are not nearly as portable and practical as X-ray machines, typically extending up to tens of meters in length and requiring powerful energy sources to generate the neutrons.

According to a University of California, Davis website: Neutron radiography is, however, suitable for a number of tasks impossible for conventional x-ray radiography. The advantage of neutrons compared to x-rays is the ability to image light elements (i.e. with low atomic numbers) such as hydrogen, water, carbon etc. In addition, neutrons penetrate heavy elements (i.e. with high atomic numbers) such as lead, titanium etc. allowing the study of materials in complex sample environments, for example water accumulation in hydrogen fuel cells. Because neutrons interact with the nucleus rather than with the electron shell, they can also distinguish between different isotopes of the same element.

“We’re looking for innovative designs and construction methods to shrink a neutron accelerator from 10 meters or longer down to 1 meter or less, similar to the size of portable X-ray tubes today,” said Vincent Tang, DARPA program manager in a statement. “Creating a high-yield, directional neutron source in a very compact package is a significant challenge. But a successful ICONS program would provide an imaging tool with significant national security applications, able to deliver very detailed, accurate internal imaging of objects in any setting.”

Neutron imaging could help detect explosives and contraband by identifying the chemical and atomic make-up of an object or its contents. And it could assist in forensics and attribution, such as differentiating sources of ammunition through imaging of the propellant fill levels, DARPA stated.